DESCRIPTION: The overall aim of the study is to measure and compare the quality of care provided to elderly patients with acute myocardial infarction (AMI) under capitation (Medicare HMOs) and Medicare fee-for-service (FFS). The study extends previous studies of adherence to AMI practice guidelines and the effect of an educational program to modify physician adherence rates. The study has two parts. Part 1 is a quantitative analysis, using observational data, some of which are previously collected, to test hypotheses about differences in quality of care by insurance status. The major hypotheses for this part of the study relate to: 1) adherence to national guidelines for effective drugs for AMI; 2) non-adherence to national guidelines for lidocaine use (when contraindicated); 3) triage delay (time from symptom onset to hospital presentation); 4) and, among thrombolytic recipients, the door-to-needle time as an outcome measure. The study sample is based on a historical inception cohort design that included patients presenting with symptoms of an MI and to the 37 study hospitals. The power calculations are based on the expectation of differences in care by insurance status. Part 2 will consist of a qualitative study to conduct in-depth interviews with key informants who are familiar with the state medical systems and with acute care for AMI. Informants will be drawn from 5 categories: HMO administrators and medical staff; hospital administrators and medical staff; staff of state Medicare and Medicaid; staff of medical indemnity plans; and local cardiology opinion leaders.